By Phil Mercer
BBC News, Sydney
The disappearance of British tourist Peter Falconio is Australia's most gripping mystery since the case of Lindy Chamberlain, the woman who said a dingo killed her baby daughter in 1980.
She was jailed for the murder of nine-week old Azaria but was later cleared and received a pardon.
Joanne Lees, who arrived in Darwin on Friday, will be a key witness
Like that of Azaria Chamberlain, Mr Falconio's body has never been found.
The child went missing at Uluru, formerly known as Ayers Rock, while the English backpacker vanished further north, near Barrow Creek four years ago.
Both cases have presented formidable challenges to the Northern Territory police.
Mr Falconio, 28, was on holiday with his girlfriend Joanne Lees. They were heading towards tropical Darwin from Alice Springs in an orange camper van.
It was after dusk on Saturday, 14 July 2001 and the Stuart Highway was almost deserted.
Prosecutors have insisted that a lone gunman then flagged the couple down, claiming that their exhaust was damaged.
It is claimed that Mr Falconio was then shot dead when he stepped from the camper van to investigate.
Miss Lees was then allegedly assaulted, tied up and dumped in the back of her assailant's truck.
Miss Lees managed to flee and hid for several hours in the desert, 160 miles (260km) north of Alice Springs.
The prosecution claims that the man responsible for this brutal ambush was Bradley John Murdoch.
The 47-year-old mechanic from the remote Western Australian town of Broome has denied charges of murder, assault and abduction.
He was ordered to stand trial after a five-week committal hearing in Darwin last year.
Miss Lees will be key to the case. Now 32, the travel agent from Brighton has again made the long journey from the south of England to Australia.
On her arrival in the Northern Territory early on Friday morning, the prosecution's star witness looked understandably nervous and tired.
The next few weeks promise to be extremely testing for Mr Falconio's former partner. During the committal hearing, Miss Lees' private life was intensely scrutinised by the defence.
She can expect much more of the same this time around.
The couple were driving a camper van across the outback
She will also be preparing to once again fix her gaze in court on the man she believes murdered her boyfriend.
The family of Mr Falconio, from Huddersfield, West Yorkshire, is also in Darwin. His parents, Luciano and Joan, are being supported by brothers Nick and Paul, who will give evidence during the trial that could last for up to two months.
Nick Falconio hopes the coming weeks will bring the family some sort of closure.
"We're apprehensive but we want to do justice for Peter," he said. "It's been a long time, over four years now, and it's time we got some conclusion."
Crown prosecutors are expected to call about 100 witnesses. It is a case that has attracted global attention and the authorities are doing all they can to make sure it runs smoothly.
A film inspired partly by the Falconio mystery has had its release in the Northern Territory postponed until after Murdoch's trial.
Lawyers were worried that the grisly thriller Wolf Creek could prejudice the hearing.
At least five books are being written in Australia about Mr Falconio, a measure of the huge interest there is in this captivating case.
There has been intrigue at almost every turn. During last year's committal hearing, two witnesses claimed they saw the missing Englishman more than a week after he was allegedly shot dead.
These extraordinary claims were made by workers at a truck stop in the outback town of Bourke. It is at least a full day's drive away from where Mr Falconio disappeared.
Robert Brown told the court that he recognised the Briton from pictures in the newspapers. "If it wasn't him, they must have been twins," the witness said.
Darwin's Supreme Court can expect more dramatic twists in the weeks ahead.